Fagor alarm 4210: Error in the SERCOS ring (MST lost)
CNC 8060/8065/8070 SERCOS error · Fagor 8060/8065/8070
What it means
The master synchronism telegram (MST) stopped arriving correctly around the loop and phase 4 collapsed. Because MST is generated by the CNC master and consumed by every slave, the break is usually in the outbound light path shared by all nodes.
Likely causes
- fiber break on the master output segment
- master control board (SERCON) transmit fault
- first slave in line powered off, halting pass-through
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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SERCOS fiber-optic ring cable assembly
cable · Common cause
Need the part urgently?
Send us alarm 4210 with your machine details — typical RFQ turnaround is 24–48h.